Over-current signal means



1933- c. B. HEFNER 1,934,264

OVER CURRENT SIGNAL MEANS Filed Dec. 4, 1930 QMJMW Patented Nov. 7, 1933 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to over-current signal means.

The usual electrical distribution system consists of feeder wires from a substation to a feed- 5 ing point. From this feeding point, or primary point, a plurality or" mains branch out, usually in at least four directions, and supply different sections. The distribution system is usually a high voltage distribution system, although this lo'invention is applicable to any voltage system whatsoever.

In the event that one of the conductors of the mains becomes short-circuited, for instance by a grounded conductor, it usually results in the opening of the automatic switch at the substation. In order to locate the trouble in accordance with the heretofore known practice, it is necessary to inspect all or" the long and circuitous lines connected to the feeding point in order to determine which of the mains has the short-circuit. This obviously consumes a large amount of time and interrupts the service of all of the mains leading from the distribution point.

Objects of this invention are to provide an over-current visual signal means which may be placed on each branch circuit, which will function automatically in the event of an overload on any branch which is of a predetermined magnitude, such, for example, as that required to open the automatic switch at the substation, and which will indicate the branch or mains upon which the short-circuit occurs, thereby avoiding the necessity of examining each of the'several branch circuits, and, consequently, reducing the tirne of interruption of the service to a minimum.

Further objects are to provide a novel form of over-current signal means which may be mounted directly upon an electrical conductor without the use of insulators or brackets, which contains no electrical coils or conductors other than that on which it is mounted, which may be adjusted to any desired predetermined value of current for which it will operate, and which may be easily re-set after the trouble on the mains has been remedied.

Further objects are to provide a simple, positive and rugged over-current signal means which is simple to construct, which may be most easily installed, which does not require connection to the electrical system, and which is wholly reliable in its operation.

Further objects are to provide an over-current visual signal means which may be mounted either indoors or outdoors, which may be readily mounted upon the overhead conductor, which may be readily viewed from the ground and will display the over-current signal in an unmistakable manner, and which may be easily re-set.

An embodiment of the invention is shown in the accompanying drawing, in which:-

Figure l is a side elevation, partlyin section, showing the device in position on a conductor, such view showing the device in its adjusted or set position.

Figure 2 is a View from the under side ofv Figure 1 with parts broken away.

Figure 3 is a side elevation, partly broken away, showing the position of the parts during actual short-circuit or overload.

Figure 4 is a view correspondingto Figure 3 showing the position of the parts after shortcircult has ceased.

Referring to the, drawing it will be seen that the device comprises a laminated core 1, which is of inverted U shape. This laminated core is 75, preferably provided with side plates 2. The entire construction is held togetherpby means of rivets or other securing means 3. The. side plates 2 extend downwardly in spaced relation, and extend rearwardly to form spaced means 4, between which the laminated armature 5 is, mounted. This laminated armature is provided with side plates 6, which extend rearwardly beyond the body of the armature to provide ears 7, which are located between theears 4. The armature laminations and the side plates thereof are held together by means of rivets or other suitable securing members 8.

It is preferable to form the laminations constituting the armature and core of galvanized 90. iron, and to form the side plates 2 and 6 of suitable non-rusting material.

A headed pivot pin 9 extends through the ears 4 and 7, as shown most clearly in Figure 2, and a split pin, or cotter pin 10 is passed through the end of the pivot pin 9 to hold such pivot pin in place.

One arm, preferably the rear arm of the core 1, is provided with a threaded aperture into which a pointed set screw 11 is screwed.

The entire device is placed upon a conductor, preferably an insulated conductor 12, and the core rests directly against the insulation surrounding the conductor. The set screw is then adjusted so that it clamps against the insulation of the conductor, as shown in Figure 1, to thereby lock the device in place.

It is to be noted that the laminated armature is provided with a core 13 directly under the forward leg of the main core 1. This core 13, or

pole, is surrounded by a conductor 14, which acts in the manner of a shading coil and delays the dying out of the magnetic flux at the zero portion of the current cycle in a well known manner.

A spring brass latch 15 is loosely pivotally supported from the core 1, as shown'in Figures 1, 3 and 4, and is adapted to be engaged by an upwardly projecting hook 16, adjustably carried by the armature. This hook is preferably formed integrally with a bottom brass strip 17 located on the under side of the armature, and it is also preferable to braze or otherwise secure a second brass strip 18 to the strip 17. The brass strip 18' means, is carried. The brass strips 17 and 18 are provided with spaced slots 2i), through Which screws 21 pass, suchscrews extending into the armature and adjustably clamping the hook 16 and associated parts in place.

It is obvious that the distance between the armature and the core or main yoke may be readily adjusted by loosening the screws 21, and sliding thehook 16 outwardly away from the arm of the armature,.or inwardlyinto the position shown in Figure. 1. The particular adjustment selected isv determined by the value of current flow for which the. device is to operate.

In the operation of the device it is clear that when. an overload occurs, for instance through a short-circuit, that the armature will bedrawn upwardly and that the hook 16 will be disengaged from the latch 15, as shown in Figure 3. When the automatic switch at the substation opens, thus tie-energizing the conductor, the armature drops downwardly into the position shown in Figure 4, thus displaying the ruby reflector 19'. This ruby reflector is now in a position where it may be readily seen from the ground. Even at night it is an extremely simple matter for a lineman equippedwith a flashlight toinspect the condition oi. the'over-current signal device.

1 It is clear that the re-setting of the device mere- 1y consists in again swinging the armature upwardly and engaging the hook 16 with the latch 15. The device may, therefore, operate an indefinite number of times without any renewal whatsoever, and without any possible danger of damage tothe device, irrespective of the magnitude'of the short-circuit current.

It-will' be seen further that the device does not necessitate opening the conductor or electrically connecting any part thereto. It is merely bodily positioned and locked in place by the set screw 11 without in any manner altering the main conductor.

It will be seen further that the device is eminently practical, is very simple, and may be most cheaply constructed.

Although this invention has been described in considerable. detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. An over-current signal means comprising a conductor, a U shaped yoke of magnetic material surrounding said conductor, means for holding said yoke in place-upon the conductor, an armature pivotally carried by said yoke, a latch normally holding said armature in spaced relation to said yoke and adapted to release when said armature is moved towards said yoke, and signal means. carried by said armature and normally held in. one position, said signal means being freely visible when said armature is released from said latch and swings away from said yoke.

2. An over-current signal means comprising a conductor; an inverted U shaped yoke surrounding said conductor, means for holding said yoke upon said conductor, an armature pivotally carried by said yoke and positioned beneath said yoke, said armature tending to move downwardly under the action of gravity, a latch restraining the motion of said armature under normal conditions, latch releasing when said armature moves upwardly under over-current conditions, and signal means carried by said armature and displayed when said armature drops downwardly after cessation of the over-current condition.

3. An over-current signal means comprising a conductor, a yoke surrounding said conductor, means for securing said yoke to said conductor, an armature pivotally carried by said yoke and tending to swing away from said yoke, and a latch normally holding said armature in spaced relation to said yoke, said latch tending to move to a. releasing position and being restrained by said armature, said latch being adapted to release said armature due to the movement of said armature towards said yoke.

CHARLES BALSER HEFNER. 

